Welding is a manufacturing process for joining materials to form a bond. In general, welding includes the fusion of the materials together, i.e., melting the base materials to join them together as a single component. Melting the base materials generates a pool of molten material (a melt pool) where the bond is formed. A filler material is often added to the melt pool to facilitate improving the properties of the bond and to fill gaps where acceptable joint fit-up cannot be achieved.
Beam welding is one process for joining materials. Examples of beam welding include laser beam welding and electron beam welding. Laser beam welding is a fusion welding process where a concentrated beam of light is directed and focused by an optical system to a concentrated spot on the materials being joined. Some laser welding systems include an aperture plate, or aperture shield, located between the workpiece and the welding head to facilitate protecting the welding head and the optical system from beam reflections and spatter from the welding process.